This invention relates to a torsional vibration damping means for a marine propulsion device and more particularly to an improved arrangement for damping torsional vibrations in the drive shaft of a marine drive.
As is well known, marine drives include drive shaft housing in which a drive shaft is rotatably journaled and which drives a propulsion device that is carried by a lower unit, positioned at the lower end of the drive shaft housing. The propulsion device may comprise either a propeller or other types of known devices utilized for this purpose. This type of marine drive is common to the outboard drive unit of an inboard/outboard drive or the drive shaft housing and lower unit of an outboard motor. The drive shaft is subject to a number of torsional vibrations and the marine propulsion unit itself adds to these torsional vibrations. Frequently, the unit also encounters shock loading such as when a propeller strikes an underwater object and this coupled with the torsional fatigue of the drive shaft can very well cause failure of the drive shaft.
It is, therefore, a principle object of this invention to provide an improved arrangement for damping torsional vibrations in the drive shaft of a marine drive.
It is another object of this invention to provide an improved arrangement for damping the torsional vibrations of the drive shaft of a marine propulsion unit.